Optical Coherence Tomography (OCT) Imaging Systems for Use in Ophthalmic Applications

ABSTRACT

Optical coherence tomography (OCT) imaging systems for imaging an eye are provided including a source having an associated source arm path and a reference arm having an associated reference arm path coupled to the source path, the reference arm path having an associated reference arm path length. A sample having an associated sample arm path coupled to the source arm and reference arm paths is provided. A reference arm path length adjustment module is coupled to the reference arm. The reference arm path length adjustment module is configured to automatically adjust the reference arm path length such that the reference arm path length is based on an eye length of the subject. Related methods and computer program products are also provided.

CLAIM OF PRIORITY

The present application is a continuation of U.S. application Ser. No.13/862,987, filed Apr. 15, 2013, which is a continuation of U.S.application Ser. No. 12/428,603, filed Apr. 23, 2009, now U.S. Pat. No.______, which claims priority to U.S. Provisional Application No.61/047,265, filed Apr. 23, 2008, the disclosures of which are herebyincorporated herein by reference as if set forth in their entirety.

STATEMENT OF GOVERNMENT SUPPORT

This invention was made with government support under grant number2R44EY015585 awarded by National Institutes of Health, National EyeInstitute. The United States Government has certain rights in thisinvention.

FIELD

The present invention relates to imaging and, more particularly, tooptical coherence tomography (OCT) and related systems, methods andcomputer program products.

BACKGROUND

Optical Coherence Tomography (OCT) systems have generally been designed,manufactured and deployed with a target to serve diagnosis of eyedisease in the adult population with a mature structure of the eye. Suchsystems are typically designed with focal optics and interferometricarrangements suitable for imaging the retinal plane, and visualizing andquantifying pathologies related to major eye diseases, such as glaucomaand macular-degeneration. Such systems are used in practice whereverappropriate, but the visibility of pathologies and the quality of imagesis constrained by design decisions that have been optimized for thedistribution of attributes of the adult eye, as eye disease in themajority of cases is demographically associated with increasing age.

A system designed for a mature eye may not be well suited for a broadrange of applications. For example, pediatric applications have theirown distinct requirements. The pediatric eye, by definition, is adeveloping eye, and the neonatal eye is considerably smaller than themature eye. With the increasing incidence of successful births ofpremature babies, pediatric patients may exhibit a broad range ofcongenital malformations and genetic disorders, frequently with adramatic deviation from normal pathology. A premature baby in theneonatal intensive care unit (NICU) may be at risk for a host of chronicdiseases, including retinopathy of prematurity, that typically requirecareful diagnosis and management. Furthermore, in pediatricophthalmology there is also a high incidence of traumatic damage due to,for example, conditions ranging from shaken-baby syndrome to accidentsgenerally associated with small children.

SUMMARY

Some embodiments of the present invention provide optical coherencetomography (OCT) imaging systems for imaging an eye including a sourcehaving an associated source arm path and a reference arm having anassociated reference arm path coupled to the source path, the referencearm path having an associated reference arm path length. A sample havingan associated sample arm path coupled to the source arm and referencearm paths is provided. A reference arm path length adjustment module iscoupled to the reference arm. The reference arm path length adjustmentmodule is configured to automatically adjust the reference arm pathlength such that the reference arm path length is based on an eye lengthof the subject.

In further embodiments of the present invention, the reference arm pathlength may be adjusted to accommodate subject eye lengths in the samplearm ranging from about 2.0 mm to about 50 mm. The reference arm pathlength may be optimized based on a sample arm optical path length towithin a prescribed offset from a focal plane of the OCT system.

In still further embodiments of the present invention, a lens systemincluding at least one lens is provided in the sample arm path and atleast one surface of the eye, the lens system having a field curvaturethat matches a curvature of a retina of the eye of the subject. The atleast one lens may be configured to image a mature eye or a pediatriceye. A distance from a cornea to a retina of the mature eye may be about25 mm and a the distance from the cornea to the retina of the pediatriceye may be from about 14 mm to about 25 mm.

In some embodiments of the present invention, the at least one lens mayhave an associated focus adjustment that enables imaging into bothanterior and posterior regions of the posterior chamber of the eye ofthe subject. In certain embodiments, the focus adjustment mayaccommodate at least +30D of additional focal power. In someembodiments, the focus adjustment may accommodate at least +50D ofadditional focal power or up to +100D of additional focal power.

In further embodiments of the present invention, the system may be awide field imaging system providing a field of view of about equal to orgreater than 50 degrees.

In still further embodiments of the present invention, the system may bea wide field imaging system providing a field of view of about equal toor greater than 140 degrees in combination with rotation about a pupil.

In some embodiments of the present invention, the reference arm pathlength adjustment module is configured to set a target reference armpath length based on an age of the subject. The reference arm pathlength adjustment module may be configured to set a target reference armpath length based on additional information pertaining to the subject.The additional information may include a refractive status of the eye ofthe subject; measured axial eye length of the subject; and/or anyrelevant test results.

In further embodiments of the present invention, the OCT system may beportable such that the OCT system is provided to the subject where thesubject is located. In some embodiments of the present invention, theportable OCT system may be configured to provide imaging to a subjectindependent of the orientation of the subject. The portable OCT systemmay be configured to be moved to a location of the subject, unpluggedand/or receive new samples without being shutdown.

In still further embodiments of the present invention, the portable OCTsystem may include a portable handheld OCT probe; a battery backupdevice associated with the portable handheld probe; and a moveable rackconfigured to receive the portable handheld probe and/or the batterybackup device.

In some embodiments of the present invention, the portable OCT systemmay further include a fixation target for the subject configured toprovide a comfort image to the subject during image acquisition. Thefixation target may be configured to provide a continuously variablepatient comfort image.

In further embodiments of the present invention, the portable OCT systemmay be configured to provide a visible light that reflects off a corneaof the eye of the subject to enable accurate positioning of the portableOCT system.

In still further embodiments of the present invention, the portable OCTsystem may include a video and/or digital fundus camera.

In some embodiments of the present invention, the portable OCT systemmay further include a foot peddle and/or finger trigger configured tocontrol focus adjustment, reference arm path length adjustment and/ortrigger acquisition of an image.

In further embodiments of the present invention, the portable OCT systemmay be configured to provide two orthogonal images to illustratepathology of an eye of the subject to facilitate aiming of the portableOCT system during image acquisition.

In still further embodiments of the present invention, the portable OCTsystem may be configured to continuously acquire images until detectionof an image capture trigger is detected; and record a predeterminedbuffered portion of the acquired image upon detection of the imagecapture trigger. In certain embodiments, the buffered image comprisesthe most recent from about 2.0 seconds to about 30 seconds of theacquired image.

In some embodiments of the present invention, the continuously acquiredimage may be streamed to a non-volatile storage for a predeterminedperiod of time.

In further embodiments of the present invention, the system includes aquality assessing module configured to display an acquired image to animage acquisition technician; trigger adjustment of the reference armpath length and/or focusing of at least one lens in the sample arm basedon an assessed quality of the displayed image; and trigger the OCTsystem to initiate or continue acquisition of the image afteradjustments are made.

In still further embodiments of the present invention the OCT system maybe configured to acquire an image from an aphakic subject.

In some embodiments of the present invention, the OCT system may be apediatric OCT system.

Further embodiments of the present invention provide OCT imaging systemsfor imaging an eye including a source having an associated source armpath and a reference arm having an associated reference arm path coupledto the source path, the reference arm path having an associatedreference arm path length. A sample having an associated sample arm pathcoupled to the source arm and reference arm paths is provided. A lenssystem having at least one lens in the sample arm path is provided. Thelens system has a field curvature based on a curvature of a retina ofthe eye of the subject

Still further embodiments of the present invention provide methods forimaging an eye in an optical coherence tomography (OCT) imaging systemincluding setting a target reference arm path length of the OCT systemsuch that the reference arm path length is based on an eye length of asubject; obtaining additional information about the subject relevant tothe target reference arm path length; recalibrating the reference armpath length based on the obtained information; and automaticallyadjusting the reference arm path length based on the recalibratedreference arm path length.

In some embodiments of the present invention, an image is acquired usingthe OCT system having the adjusted reference arm path length. The methodmay further include assessing the image quality of the acquired image;determining if the adjusted reference arm path length is optimum;further adjusting the reference arm path length if it is determined thatthe adjusted reference arm path length is not optimum; and reacquiringthe image using the OCT system having the further adjusted reference armpath length.

In further embodiments of the present invention, the steps of assessing,determining, further adjusting and reacquiring may be repeated until animage having a desired quality is obtained.

In still further embodiments of the present invention, further adjustingis followed by determining if a focus of at least one objective lens ofthe OCT system is optimum; and adjusting focus position of the at leastone objective lens of the OCT system if it is determined that the focusof the at least one objective lens is not optimum, wherein reacquiringthe image further comprises reacquiring the image using the OCT systemhaving the further adjusted reference arm path length and the adjustedfocus.

Some embodiments of the present invention provide computer programproducts for imaging an eye in OCT imaging systems including computerreadable storage medium having computer readable program code embodiedin said medium. The computer readable program code includes computerreadable program code configured to set a target reference arm pathlength of the OCT system such that the reference arm path length isbased on an eye length of a subject; computer readable program codeconfigured to obtain additional information about the subject relevantto the target reference arm path length; computer readable program codeconfigured to recalibrate the reference arm path length based on theobtained information; computer readable program code configured toautomatically adjust the reference arm path length based on therecalibrated reference arm path length; and computer readable programcode configured to acquire an image using the OCT system having theadjusted reference arm path length and display the acquired image on anelectronic display associated with the OCT system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a Fourier domain retinal opticalcoherence tomography system in accordance with some embodiments of thepresent invention.

FIG. 2 is a block diagram illustrating a lens configuration forEmmetropic telecentric retinal imaging in accordance with someembodiments of the present invention.

FIG. 3 is a block diagram illustrating a lens configuration for ahyper-focal retinal imaging for blastoma imaging in accordance with someembodiments of the present invention.

FIG. 4 is a block diagram illustrating a lens configuration for ahypo-focal retinal imaging for aphakia without system accommodation inaccordance with some embodiments of the present invention.

FIG. 5 is a block diagram illustrating a lens configuration for hyporetinal imaging aphakia with system accommodation in accordance withsome embodiments of the present invention.

FIG. 6 is a block diagram illustrating a lens configuration for retinalimaging, with system accommodation for varying developmental eye lengthsin accordance with some embodiments of the present invention.

FIGS. 7A through 7C are diagrams illustrating focal field curvatureoptimization to posterior pole radius of curvature in accordance withsome embodiments of the present invention.

FIG. 8 is a flowchart illustrating focus and reference optimizationoperations in accordance with some embodiments of the present invention.

FIG. 9 is a block diagram illustrating a portable OCT system inaccordance with some embodiments of the present invention.

FIG. 10 is a graph of normalized illuminance vs. wavelength illustratingwavelength allocation of optical path lengths scan head in accordancewith some embodiments of the present invention.

FIG. 11 is a graph of spot diameter vs. angle illustrating field of viewdefined by lateral resolution imaging pediatric eye with differentoptics in accordance with some embodiments of the present invention.

FIG. 12 is a block diagram illustrating a multi-function scanner systemincluding OCT, video or digital fundus image capture, fundusillumination, and discrete or variable fixation target in accordancewith some embodiments of the present invention.

FIG. 13 is a diagram of an exemplary fixation target and excitationsource in accordance with some embodiments of the present invention.

FIG. 14 is a diagram illustrating a mechanical concept for the portableOCT system in accordance with some embodiments of the present invention.

FIG. 15 is a ZEMAX rendering of an optical design for a portable OCTsystem in accordance with some embodiments of the present invention.

FIG. 16 is ZEMAX diagram illustrating how the design of the portable OCTsystem allows viewing of the most peripheral retina in accordance withsome embodiments of the present invention.

FIG. 17 is a solidworks illustration of a design for the portable OCToptics barrel in accordance with some embodiments of the presentinvention.

FIG. 18 is a solidworks illustration of a reference arm design with axesfor motorized control to translate a retroreflector in accordance withsome embodiments of the present invention.

FIG. 19 is a block diagram of a data processing system suitable for usein some embodiments of the present invention.

FIG. 20 is a more detailed block diagram of a system according to someembodiments of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The present invention will be described more fully hereinafter withreference to the accompanying figures, in which embodiments of theinvention are shown. This invention may, however, be embodied in manyalternate forms and should not be construed as limited to theembodiments set forth herein.

Accordingly, while the invention is susceptible to various modificationsand alternative forms, specific embodiments thereof are shown by way ofexample in the drawings and will herein be described in detail. Itshould be understood, however, that there is no intent to limit theinvention to the particular forms disclosed, but on the contrary, theinvention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the invention as defined by theclaims. Like numbers refer to like elements throughout the descriptionof the figures.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”,“comprising,” “includes” and/or “including” when used in thisspecification, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof. Moreover, whenan element is referred to as being “responsive” or “connected” toanother element, it can be directly responsive or connected to the otherelement, or intervening elements may be present. In contrast, when anelement is referred to as being “directly responsive” or “directlyconnected” to another element, there are no intervening elementspresent. As used herein the term “and/or” includes any and allcombinations of one or more of the associated listed items and may beabbreviated as “/”.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms used herein should be interpreted ashaving a meaning that is consistent with their meaning in the context ofthis specification and the relevant art and will not be interpreted inan idealized or overly formal sense unless expressly so defined herein.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another. For example, a first element could be termed asecond element, and, similarly, a second element could be termed a firstelement without departing from the teachings of the disclosure. Althoughsome of the diagrams include arrows on communication paths to show aprimary direction of communication, it is to be understood thatcommunication may occur in the opposite direction to the depictedarrows.

Conventional OCT imaging systems are designed to image a mature adulteye. OCT imaging systems directed to the pediatric population willtypically require specific optics for the pre-adolescent eye, anincreased dynamic range of performance attributes including field ofview, focal adjustments, and interferometric path length matchingconditions and the like. However, the pediatric patient is not wellsuited to a standard clinical imaging system designed for the matureadult eye. Accordingly, an imaging system that is directed to a smaller,uncooperative patient, whether in the clinic or in the operating suite,may be desired for more accurate, successful imaging.

Thus, some embodiments of the present invention provide acoherence-gated imaging system (optical coherence tomography (OCT)system) that provides high resolution depth-resolved images of retinalpathologies over a broad field of view in patients with eyes rangingfrom the premature underdeveloped eye to the fully developed eye, withadjustment capabilities to observe disease, trauma, and malformations,in environments from the clinic, to the operating suite, to the fieldand the like as will be discussed further below with respect to FIGS. 1through 20.

In particular, some embodiments of the present invention provide an OCTsystem, for example, a Spectral Domain (SD) OCT system, specificallydesigned for pediatric patients is described. As discussed herein, OCTsystems in accordance with some embodiments of the present inventioninclude an electromechanical mechanism to manually or automaticallyadjust a reference arm path length. The OCT system is configured toestimate an initial reference arm path length (axial length) based oninformation such as the age of the patient, refractive status of thepatient's eye and the like. The OCT delivery optics (i.e. the patientinterface) include lenses with a relatively larger field of view thanprovided by conventional systems, which may enable examination of theentire retina including the periphery. Furthermore, the small physicalsize of the final stage of these lenses may allow a portable OCT systemin accordance with some embodiments of the present invention to be aimedwidely within the patient's orbit.

Referring first to FIG. 1, a block diagram illustrating a Fourier domainretinal OCT system in accordance with some embodiments of the presentinvention will be discussed. As illustrated in FIG. 1, the systemincludes a low coherence source 100, a reference arm 300 and a samplearm 400 coupled to each other by a beamsplitter 200. The beamsplitter200 may be, for example, a fiber optic coupler or a bulk or micro-opticcoupler without departing from the scope of the present invention. Insome embodiments, the beamsplitter 200 may provide from about a 50/50 toabout a 90/10 split ratio, with the larger fractional power directed tothe reference arm path. As further illustrated in FIG. 1, thebeamsplitter 200 is also coupled to a frequency sampled detection module600 over a path 605 that may be provided by an optical fiber.

As further illustrated in FIG. 1, the source 100 is coupled to thebeamsplitter 200 by a source path 105. The source 100 may be, forexample, an SLED or tunable source. The reference arm 300 is coupled tothe beamsplitter over a reference arm path 305. Similarly, the samplearm 400 is coupled to the beamsplitter 200 over the sample arm path 405.In some embodiments of the present invention, the source path 105, thereference arm path 305 and the sample arm path 405 may all be providedby optical fiber.

In accordance with some embodiment of the present invention, thereference arm 300 further includes a collimator assembly 310, a variableattenuator 320 that can be neutral density or variable aperture, amirror assembly 330, a reference arm variable path length adjustment 340and a path length matching position 345, i.e. optical path lengthreference to the eye 500. As further illustrated, the sample arm 400according to some embodiments of the present invention may include adual-axis scanner assembly 410 and an objective lens variable focus 420.

The sample in FIG. 1 is an eye 500 including a cornea 510, iris/pupil520, ocular lens 530 and eye length 540. As will be discussed in detailherein, the eye length 540 in accordance with some embodiments of thepresent invention may be a subject specific, age dependent, pathologydependent axial optical eye length.

As further illustrated in FIG. 1, a representation of an OCT imagingwindow 700 is illustrated near the eye 500. The OCT imaging window isthe depth over which the SD-OCT system provides an image. The windowdepth is well-known to be a function of the sampling interval of thespectral interferogram. The window depth is measured from the position345 in the sample arm path at which the optical path length matches thereference arm optical path length. An image may be acquired for samplepositions greater than or less than the reference arm path length, suchselection is a function of operator choice and software image processingalgorithms.

OCT systems in accordance with some embodiments of the present inventionare configured with a reference arm path length adjustment module 340.The reference arm path length adjustment module may include anycombination of the collimator assembly 310, the variable attenuator 320,the mirror assembly 330, the reference arm variable path lengthadjustment 340 and the path length matching position 345 of thereference arm 300 discussed above. In particular, the reference arm pathlength adjustment module 340 is configured to manually or automaticallyadjust the reference arm path length such that the reference arm pathlength is based on an eye length of the subject 540. The presence ofthis module allows the OCT system to adjust to patients having differenteye lengths 540, thus allowing eyes of patients having immature eyes(pediatric patients), for example, eyes having a length of less than 25mm, to be accurately imaged. Eye length is measured as the distancebetween the cornea 510 and the retina. A mature adult eye typically hasa length of about 25 mm and a pediatric eye length can be from about 14mm to about 25 mm. Accordingly, the reference arm path length adjustmentmodule in accordance with some embodiments of the present invention maybe made capable to accommodate eye lengths ranging from about 10 mm toabout 30 mm, and preferable to accommodate eye lengths ranging fromabout 2 mm to about 50 mm, to accommodate fetal development and themature eye of larger animal models. The reference arm optical pathlength may be optimized to correspond with a prescribed range of offsetsto a sample arm optical path length as measured to a focal plane of theOCT system. The reference arm path length may generally be selected tobe offset from the sample arm path length as measured to a focal planeof the OCT imaging system with a range of 0 mm to 2 mm, and may be lessthan or greater than the corresponding sample arm path length.

In some embodiments of the present invention, the reference arm pathlength adjustment module is configured to set a target reference armpath length based on an age of the subject and/or a refractive status ofthe eye of the subject. The target reference arm path length may be setusing the patient's age and a standard table for the growth of an eye.Such a table may be found in, for example, A longitudinal study of thebiometric and refractive changes in full-term infants during the firstyear of life by Pennie et al, Vision Research 41 (2001, 2799-2810). Thistarget reference arm path length may then be fine tuned based onadditional information pertaining to the subject that may be obtained,for example, the patient's actual measured eye length, ultrasoundresults or other relevant test results. The reference arm path lengthmay then be adjusted based on this additional information to provide amore accurate OCT image.

As discussed above, OCT systems in accordance with some embodiments ofthe present invention may further include at least one lens in thesample arm path 405 (scanner assembly 410) such that the at least onelens in combination with the optical attributes of the subject eye has afield curvature that matches a curvature of a retina of the eye of thesubject. In other words, the lenses may be switched to conform to theeye length, for example, 25 mm or 14 mm, of the patient. Thus, OCTsystems discussed herein can be configured to image both a mature eyeand a pediatric eye. OCT systems in accordance with some embodiments ofthe present invention provide a wide field imaging system providing afield of view of up to about 50 degrees. In combination with rotationaround the pupil of the eye, the pediatric lens provides a field of viewof 140 degrees.

As discussed above, the scanner assembly 410 including the at least onelens has an associated focus adjustment provided by, for example, theobjective lens variable focus 420, that enables imaging into bothanterior and posterior regions of the posterior chamber of the eye ofthe subject. Conventional systems do adjust for normal refractive errorsin an adult population. Such adult-oriented systems have focaladjustment over the range of +−12 Diopters, to a maximum of +−20Diopters. It is more critical in the pediatric population to provideoptics that can accommodate the range of congenital and traumaticpathologies of this population. Such pathologies include blastomas,requiring increased optical power to focus above the retina as much as 3to 4 mm, and aphakia (lack of ocular lens), requiring increased opticalpower to overcome the lack of an ocular lens. In the most extreme caseof an aphakic child with a severe blastoma or calcification, such thatit is desirable to image as far forward as the posterior plane of theiris, +110 Diopters of focal power are required.

Some embodiments of the present invention may provide lens that allowacquisition of an image from an aphakic patient, i.e. a subject thatdoes not have an ocular lens in the eye or to image a patient with ablastoma or calcification on or above the retina of the eye. The lens ofthe present invention has a focal range from −12 Diopters to +50Diopters, with an option to increase the power to +100 Diopters byincreasing the zoom and decreasing the working distance to the subject.The reference arm must be adjusted to accommodate the effectivereduction in sample optical path length accordingly.

Standard imaging systems are fixed in a single location and, therefore,patients must be brought to the imaging system. As one can imagine, somepatients cannot be brought to the system and, therefore, these patientsmay not be provided with accurate images on which to make a diagnosis.Accordingly, in accordance with some embodiments of the presentinvention, the OCT system is portable such that the OCT the system isprovided to the subject where the subject is located. Thus, portable OCTsystems in accordance with some embodiments of the present invention maybe moved to a location of the subject, unplugged and/or receive newsamples without being shutdown.

As illustrated in FIG. 9, portable OCT systems in accordance with someembodiments of the present invention may include a portable handheld OCTprobe 990, which will be discussed further below with respect to FIG.12, a battery backup device 991 associated with the portable handheldprobe, such as a uninterruptable power supply (UPS), and a moveable rack992 configured to receive the portable handheld probe and/or the batterybackup device.

The portable OCT system may further include a fixation target for thesubject as illustrated in FIG. 13. As illustrated in FIG. 13, acontinuous dynamic fixation target and excitation source featuring aliquid crystal display (LCD), organic light emitting diode (OLED)displays, scanning or projection microdisplays, and animated targets forpatient comfort will be discussed. In particular, a fixation display 800associated with the portable OCT system may include a dynamic fixationicon 810 configured to provide a comfort image to the subject duringimage acquisition. In some embodiments, the fixation target (icon) 810is configured to provide a continuously variable patient comfort image.

The provision of the fixation target 810 may allow a pediatric patientwho is awake during image acquisition to relax and, thus, enablingacquisition of a more accurate image. The fixation target 810 may be anypatient comfort image, such as a static or animate cartoon character oricon, without departing from the scope of the present invention.

Portable OCT systems in accordance with some embodiments of the presentinvention may also provide visible light that reflects off the cornea ofthe eye of the subject to enable accurate positioning of the portableOCT system. In some embodiments, the portable OCT system may include avideo and/or digital fundus camera as discussed further below. In someembodiments, the portable OCT system further includes a foot peddleand/or finger trigger configured to control focus adjustment, referencearm path length adjustment and/or trigger acquisition of an image. Instill further embodiments of the present invention, the portable OCTsystem may further include a foot peddle and/or finger triggerconfigured to control the OCT source power, attenuation of OCT signalpower in the reference arm path, the power of the illumination for thevideo or digital fundus camera.

Images may be acquired using the portable OCT system using many methods.For example, the portable OCT system may provide two synchronous imagesto illustrate orthogonal pathology of an eye of the subject tofacilitate aiming of the portable OCT system during image acquisition.In other words, the device may be aimed at the portion of the eye to beimaged, present images of nasal-temporal (horizontal) physiologyside-by-side with images of inferior-superior (vertical) physiology andacquired by pushing a capture button on the device.

In some embodiments, the portable OCT system may be configured toacquire, process and display images until an image capture button isactivated at which point a most recent portion of the acquired image isstored in a buffer having a predetermined size. In some embodiments, thebuffered image may include the most recent from about 2.0 seconds toabout 30 seconds of the acquired image. In certain embodiments, thecontinuously acquired image may be streamed to non-volatile memory in afirst-in, first-out fashion for a predetermined period of time, suchthat, for example, a half hour or more of streaming image may becaptured.

Some OCT systems according to embodiments of the present inventionprovide a quality-assessment module configured to provide a figure ofmerit for the quality of an acquired image. In particular, the qualityassessment module is configured to display a figure of merit of an imageacquisition technician, trigger adjustment of the reference arm pathlength and or focusing of at least one lens in the sample arm based onan assessed quality of the displayed image and trigger the OCT system toinitiate or continue acquisition of the image after adjustments aremade. The figure of merit may be a measure of brightness of the image,and may be computed numerically and compared against a baseline of thesystem, or may be assessed qualitatively by the photographer.

Accordingly, systems according to some embodiments of the presentinvention are configured to optimize placement of reference pathmatching system to within a prescribed distance of a focal plane of theoptical system. In other words, OCT systems discussed herein areconfigured to focus on the correct place in the eye/sample and match thepath length to the subject retina or other target physiology orpathology. Thus, some embodiments of the present invention providemethods of providing path matching conditions coordinated to focalconditions for target surfaces. This is in contrast to conventionalsystems where adjustments to the reference arm path length are made tomake minor corrections to a position of an image on a screen, but arenot made to coordinate subject eye length, focus and optimum position ofreference arm length. As discussed above, conventional systems aredesigned for a mature eye having a path length of about 25 mm.

In particular, the pediatric population and adult population experiencedrastically different problems with their eyes. Pediatric patients havetypically suffered a trauma or have a congenital malformation that iswell away from the retinal plane typically imaged in adult patients.Accordingly, as discussed above, some embodiments of the presentinvention provide variable reference arm path lengths and adjustableobjective lens focusing that allow imaging of portions of the eye morerelevant to pediatric patients. Conventional systems do not provide forimaging of pediatric (immature) eyes having eye lengths of less thanabout 25 mm. Accordingly, some embodiments of the present inventionprovide a much needed pediatric OCT system as discussed herein.

Referring now to FIGS. 2 through 6, lens configurations for variousretinal imaging in accordance with various embodiments of the presentinvention will be discussed. FIG. 2 illustrates a lens configuration forEmmetropic telecentric retinal imaging in accordance with someembodiments of the present invention. FIG. 3 illustrates a lensconfiguration for a hyper-focal retinal imaging for blastoma imaging inaccordance with some embodiments of the present invention. FIG. 4illustrates a lens configuration for a Hypo-focal retinal imaging foraphakia without system accommodation in accordance with some embodimentsof the present invention. FIG. 5 illustrates a lens configuration forhypo retinal imaging aphakia with system accommodation in accordancewith some embodiments of the present invention. FIG. 6 illustrates alens configuration for retinal imaging, system with accommodation forvarying developmental eye lengths in accordance with some embodiments ofthe present invention.

Some or all of the following measurements are relevant to the lensconfigurations of FIGS. 2 through 6 as illustrated thereon. L_1 is thetelecentric objective lens separation; L_2 is the working distance fromthe lens to cornea 510; L_3 is the anterior eye length; L_4 is theposterior eye length; L_5 is the axial eye length (L_5=L_3+L_4); L_6 isthe SDOCT imaging window depth; L_7 is the offset between path lengthmatched condition and focus (|L_7|=|L_8−L_9|); L_8 is the sample armoptical path length (to focal beam waist); L_9 is the reference armoptical path length; L_10 is the change in objective lens separation L_1for change in focusing power; L_11 is the effective posterior eye lengthto subject pathology; L_12 is the effective axial eye length(L_12=L_3+L_11); L_14 is the sample arm optical path length forhyper-focal imaging; and L_15 is adjusted reference arm optical pathlength for hyper-focal imaging. A zoom range L_1 enables a focal powerof +100 Diopters.

Using these values in accordance with some embodiments of the presentinvention, Δref is the change in reference arm optical path lengthL_i−L_9, for example, L_15−L_9 for emmetropic-to-hyper-focal imaging.Δsamp is the change in sample arm optical path length L_j−L_8, forexample, L_14−L_8 for emmetropic-to-hyper-focal imaging. |Δref−Δsamp|=ε,ε<L_6 is the change in reference arm and sample arm length. This changeneed not be precisely equal but will be unequal by only a small amount εthat is less than the SDOCT window depth.

Referring now to FIG. 6, a lens configuration for a retinal imagingsystem accommodating for varying developmental eye lengths isillustrated therein. L_21 is the adjusted reference arm optical pathlength for a maturing eye, arbitrary developmental age 1. L_22 is theadjusted reference arm optical path length for a maturing eye, arbitrarydevelopmental age 2. L_23 is the adjusted reference arm optical pathlength for a mature eye.

Referring now to FIGS. 7A through 7C, diagrams illustrating Focal fieldcurvature optimization to posterior pole radius of curvature inaccordance with some embodiments of the present invention will bediscussed. The following values are relevant to the values illustratedin FIGS. 7A through 7C. D_1 is the optical power of pediatric cornea;D_2 is the optical power of pediatric lens; D_3 is the optical power ofadult cornea; D_4 is the optical power of adult lens; L_5 is thepediatric axial eye length (optical length); L_23 is the adult axial eyelength (optical length); R_1 is the radius of curvature of pediatricposterior pole; R_2 is the radius of curvature of adult posterior pole;R_3 is the field curvature of pediatric imaging optic at pediatricposterior pole; R_4 is the field radius of curvature of adult imagingoptic at pediatric posterior pole; R_5 is the field radius of curvatureof pediatric imaging optic at adult posterior pole; N_1 is therefractive index of cornea; N_2 is the refractive index of lens; N_3 isthe refractive index of vitreous humor; <N> is the effective(path-averaged) refractive index of eye. Furthermore, representativevalues are as follows D_1 is 60 Diopters; D_2 is 30 Diopters; D_3 is 43Diopters; D_4 is 21 Diopters; L_5 is 20 mm; L_23 is 34 mm; R_1 is 7 mm;R_2 is 12 mm; R_3 is 7 mm; R_4 is 6 mm; R_5 is 9 mm; N_1 is 1.38; N_2 is1.57; N_3 1.33 and <N> is 1.37.

Taking these values into account, FIG. 7A illustrates a pediatric eyeusing pediatric optimized optics in the OCT system; FIG. 7B illustratesa pediatric eye using adult optimized optics in the OCT system; and FIG.7C illustrates an adult eye using pediatric optimized optics in the OCTsystem.

FIG. 8 is a flowchart illustrating focus and reference optimizationoperations in accordance with some embodiments of the present invention.Operations begin at block 900 by obtaining patient data, such as age ofthe patient, measure axial eye length of the patient, eye length basedon chart for eye growth, refractive correction information and the like,Once the patient data is complete (block 900), a target focus correctionand a target reference arm position as discussed above with respect toFIG. 1 are set (blocks 910 and 920). Once the focus correction andreference arm position are set, imaging of the subject may commence(block 930). Once the image is obtained and displayed to the imageacquisition technician, the image may be assessed for quality (block940). The image may be assessed for qualities such as visual imagebrightness, visual field curvature, automated image quality metric,automated interferogram quality metric and the like. Based on the imagequality assessment (block 940), it is determined if the reference armposition is optimum (block 950 If it is determined that the referencearm position is not optimum (block 950), the reference arm position maybe adjusted (block 960) and a new image may be acquired using theadjusted reference arm position (block 930). Once the reference armposition is correct the focus may be optimized. Similarly, based on theimage quality assessment (block 940), it is determined if the focuscorrection is optimum (block 970). If it is determined that the focuscorrection is not optimum (block 970), the focus position may beadjusted (block 980) and a new image may be acquired using the adjustedfocus position (block 930).

If it is determined that both the reference arm position and the focusposition are optimum (blocks 950 and 970), the image may be acquiredusing the fully adjusted OCT system in accordance with some embodimentsof the present invention (block 990). Acquisition of the image (block990) may include display of the image on an electronic displayassociated with the OCT system.

Although embodiments of the present invention discussed with respect toFIG. 8 discuss adjustment of the reference arm position first and thenadjustment of the focus position, embodiments of the present inventionare not limited to this configuration. For example, the steps could bereversed or performed simultaneously without departing from the scope ofthe present invention.

FIG. 10 is a graph of normalized illuminance vs. wavelength illustratingwavelength allocation of optical path lengths scan head in accordancewith some embodiments of the present invention. FIG. 11 is a graph ofspot diameter vs. angle illustrating Field of view by lateral resolutionimaging pediatric eye with different optics in accordance with someembodiments of the present invention. The (a) curve of FIG. 11illustrates results using pediatric optimized optics and the (b) curveillustrates results using adult-optimized optics.

FIG. 12 is a block diagram illustrating a multi-function scanner systemincluding OCT, video or digital fundus image capture, fundusillumination, and discrete or variable fixation target in accordancewith some embodiments of the present invention. In some embodiments,FIG. 12 illustrates a portable OCT system in accordance with someembodiments of the present invention.

As illustrated in FIG. 12, an exemplary SDOCT system 1200 designed forpediatric and other non-standard patients is illustrated. The optical ofthe system 1200 of FIG. 12 combines the three primary functions of SDOCTscanning, video fundus illumination and imaging, and a video fixationtarget-all at a size smaller than currently available handheld slitlampand fundus camera implementations. The front objective lens forms animage of the retina and then the image is relayed into four paths viabeamsplitters. The objective lens has a variable focus and in someembodiments a manual translation capability to accommodate a −12D to+50D diopter range of patient spherical error. The working distance tothe subject eye is 20 mm.

The OCT path includes a short pass filter configured to reflectwavelengths from 820 nm to 950 nm and transmit wavelengths below 800 nmfor the fixation and fundus paths. The OCT path uses a 3 mm diameterfiber collimator incident on the 2D scanner, with a lens to form animage or the fiber at the retina image plane. The combined focal lengthsof the objective and OCT lens are designed to deliver a 2 mm diametercollimated beam on the cornea. This may yield a 16 um diameter Gaussianspot on the retina. The pivot point of the scanner and the pupil on theeye are conjugate points. Thus, scanning through the amydriatic eye maybe possible.

The fundus imaging and illumination path provide video-rate fundusimaging simultaneously with SDOCT imaging may be used as an aid toreal-time alignment of the SDOCT probe. A 700 nm LED may be used forillumination providing patient comfort and to provide a clear view ofthe color microdisplay used for fixation. In some embodiments, the CCDto be used will be an NIR enhanced Sony ⅓″ CCD. The technique used forreducing and possibly eliminating glare may use cross polarization witha polarization beamsplitter (PBS) to co-align the illumination andimaging paths. Ring illumination may reduce glare from the cornea.

As further discussed above, some embodiments of the present inventionprovided a good-quality video/digital fundus camera. Mechanicalconsiderations such as the weight, shape and balance of the scanner, aswell as ergonomic considerations such as how the operator views theresulting images while manipulating the scanner are variables that canproduce success. An exemplary mechanical concept for the case andoperator interface design of the handheld scanner is illustrated in FIG.14. This design includes a case designed to be steadied by being held inboth hands, with a rotational Diopter adjustment on the barrel. Thenovel ergonomic features of the design include a miniature landscapevideo display for side-by-side simultaneous observation of video fundusand SDOCT images, as well as buttons and controls embedded into thecasing to allow for control of SDOCT data acquisition fully independentof the computer keyboard. It will be understood that FIG. 14 is providedfor exemplary purposes only and, therefore, embodiments of the presentinvention are not limited to this configuration.

As discussed above, some embodiments of the present invention provide ahandheld SDOCT device for pediatric imaging configured with high-speedOCT scanning optics (with expanded FOV and ‘iris camera’ performance forease of use) suitable for 2D and 3D retinal imaging as illustrated inFIG. 15. FIG. 15 illustrates a ZEMAX rendering of an exemplary opticaldesign to provide greatly increased FOV, for example, 66° Withdiffraction limited spot size ≦10 um. This design utilizes smallerdiameter lenses to allow much closer approach to the eye past the nose,orbital rim, etc as illustrated in FIG. 16. Working distance may beabout 20 mm in some embodiments.

FIG. 16 is a ZEMAX illustration of how the system in accordance withsome embodiments of the present invention with smaller lenses allowsviewing the most peripheral retina (with spot radius ≦13 um) by allowingvery oblique approach (to 60° from the temporal and inferior directions,and about 45° from the nasal and superior directions as shown in theschematic eye of a newborn.

In some embodiments of the present invention, a diopter-calibratedmanual twist focus control capable of- −12D to +50D adjustment isprovided on the system as illustrated in FIG. 17. In particular, FIG. 17is a Solidworks illustration of a design for the portable OCT systemsoptics barrel, with calibrated manual twist focus control capable of−12D to +50 D adjustment to allow users to obtain good focus on theretina for 99%+ of the pediatric and general population. FIG. 18 is aSolidworks illustration of a reference arm design with axes formotorized control to translate a retroreflector (corner cube), allowingrapid access to a range of OPLs sufficient to accept 99% of thepediatric and general population.

As discussed above, the initial set point for the reference arm lengthfor patients who eye length (AL) has not been measured, will be setaccording to an estimate of AL based on patient age (in pediatricpatients) and refractive state (if known). Furthermore, in addition topre-setting the reference arm length to match the expected AL of thepatient based on prior A-scan measurement or correlation with patientage and SER, an automatic reference arm tracking of retinal position mayalso be included in some embodiments of the present invention. Retinaltracking may be implemented using a new compact, motorized reference armdesign illustrated in FIG. 18 and control software. This new referencearm design may be adjustable over 200 mm of axial motion, well in excessof the variation in AL expected among the pediatric population and withenough extra length to permit tracking 50 mm of patient/operatorrelative motion. In some embodiments, the reference arm is driven by acomputer-controlled stepper motor which can translate the delay up to110 mm/sec, which is sufficient to follow operator manipulations of theprobe and most patient/operator relative motions. The reference armposition may be controlled by a simple and fast image processingalgorithm which will search a subset of SDOCT image A-scans spreadacross the lateral scan dimension for the prominent ILM reflection, anduse this reflection to maintain the reference arm at a position whichplaces the retinal OCT image at the optimal SNR position within theimage frame. The ILM reflection can be readily identified on retinal OCTA-scans by a simple threshold algorithm. To keep the algorithm fromlocking onto other ocular structures (such as the cornea and lenscapsule as the probe is advanced), the operator will turn on retinaltracking using a foot pedal switch only after the macular reflection hasbeen obtained. There is no risk to either patient or operator from thiscontrol mechanism, which is contained within the engine chassis.

As discussed above, some aspects of the present invention may beimplemented by a data processing system. Exemplary embodiments of a dataprocessing system 130 configured in accordance with embodiments of thepresent invention will be discussed with respect to FIG. 19. The dataprocessing system 1930 may include a user interface 1944, including, forexample, input device(s) such as a keyboard or keypad, a display, aspeaker and/or microphone, and a memory 1936 that communicate with aprocessor 1938. The data processing system 1930 may further include I/Odata port(s) 1946 that also communicates with the processor 1938. TheI/O data ports 1946 can be used to transfer information between the dataprocessing system 1930 and another computer system or a network using,for example, an Internet Protocol (IP) connection. These components maybe conventional components such as those used in many conventional dataprocessing systems, which may be configured to operate as describedherein.

Referring now to FIG. 20, a more detailed block diagram of a dataprocessing system of FIG. 19 is provided that illustrates systems,methods, and computer program products in accordance with someembodiments of the present invention will now be discussed. Asillustrated in FIG. 20, the processor 1938 communicates with the memory1936 via an address/data bus 2048, the I/O data ports 1946 viaaddress/data bus 2049 and the electronic display 1939 via address/databus 2050. The processor 1938 can be any commercially available or customenterprise, application, personal, pervasive and/or embeddedmicroprocessor, microcontroller, digital signal processor or the like.The memory 1936 may include any memory device containing the softwareand data used to implement the functionality of the data processingsystem 1930. The memory 1936 can include, but is not limited to, thefollowing types of devices: ROM, PROM, EPROM, EEPROM, flash memory,SRAM, and DRAM.

As further illustrated in FIG. 20, the memory 136 may include severalcategories of software and data used in the system: an operating system2052; application programs 2054; input/output (I/O) device drivers 2058;and data 2056. As will be appreciated by those of skill in the art, theoperating system 2052 may be any operating system suitable for use witha data processing system, such as OS/2, AIX or zOS from InternationalBusiness Machines Corporation, Armonk, N.Y., Windows95, Windows98,Windows2000 or WindowsXP, or Windows CE from Microsoft Corporation,Redmond, Wash., Palm OS, Symbian OS, Cisco IOS, VxWorks, Unix or Linux.The I/O device drivers 2058 typically include software routines assessedthrough the operating system 2052 by the application programs 2054 tocommunicate with devices such as the I/O data port(s) 1946 and certainmemory 1936 components. The application programs 2054 are illustrativeof the programs that implement the various features of the someembodiments of the present invention and may include at least oneapplication that supports operations according to embodiments of thepresent invention. Finally, as illustrated, the data 2056 may includecaptured buffer data 2059 and streamed data 260, which may represent thestatic and dynamic data used by the application programs 2054, theoperating system 2052, the I/O device drivers 2058, and other softwareprograms that may reside in the memory 1036.

As further illustrated in FIG. 20, according to some embodiments of thepresent invention, the application programs 2054 include a reference armpath length adjustment module 2065 and a quality assessing module 2070.While the present invention is illustrated with reference to thereference arm path length adjustment module 2065 and the qualityassessing module 2070 as being application programs in FIG. 20, as willbe appreciated by those of skill in the art, other configurations fallwithin the scope of the present invention. For example, rather thanbeing application programs 2054, these circuits and modules may also beincorporated into the operating system 2052 or other such logicaldivision of the data processing system. Furthermore, while the referencearm path length adjustment module 2065 and the quality assessing module2070 are illustrated in a single system, as will be appreciated by thoseof skill in the art, such functionality may be distributed across one ormore systems. Thus, the present invention should not be construed aslimited to the configuration illustrated in FIG. 20, but may be providedby other arrangements and/or divisions of functions between dataprocessing systems. For example, although FIG. 20 is illustrated ashaving various circuits, one or more of these circuits may be combinedwithout departing from the scope of the present invention.

Details of operations of the reference arm path length adjustment module2065 are discussed above. The quality assessing module 2070 isconfigured to aid a technician in assessing the quality of an imagecreating using systems in accordance with some embodiments of thepresent invention. In some embodiments, the quality assessing module maybe configured to display an acquired image to an image acquisitiontechnician; trigger adjustment of the reference arm path length and/orfocusing of at least one lens in the sample arm based on an assessedquality of the displayed image; and trigger the OCT system to initiateor continue acquisition of the image after adjustments are made.

Some embodiments of the present invention provide optical coherencetomography (OCT) imaging systems for imaging an eye including a sourcehaving an associated source arm path and a reference arm having anassociated reference arm path coupled to the source path, the referencearm path having an associated reference arm path length. A sample havingan associated sample arm path coupled to the source arm and a detectorpath having a detector are provided. The sample path and the referencepath couple to the detector path to provide an interferometric opticalsignal to the detector. A reference arm path length adjustment module iscoupled to the reference arm. The reference arm path length adjustmentmodule is configured to adjust the reference arm path length such thatthe reference arm path length is matched to the sample arm path lengththat includes an eye length of the subject.

In further embodiments of the present invention, the OCT imaging systemis a Fourier domain optical coherence tomography (FD-OCT) imagingsystem. The FD-OCT imaging system may be a Spectral-domain OCT (SD-OCT)imaging system. SD-OCT uses a broadband light source and achievesspectral discrimination with a dispersive spectrometer in the detectorarm. Alternatively, the FD-OCT imaging system may be a swept-source OCT(SS-OCT) imaging system. SS-OCT time-encodes wavenumber by rapidlytuning a narrowband source through a broad optical bandwidth. The FD-OCTimaging system may utilize aspects of both SD-OCT and SS-OCT. In furtherembodiments of the present invention, the reference arm path length maybe adjusted to accommodate eye lengths ranging from about 10 mm to about30 mm, and preferable to accommodate eye lengths ranging from about 2 mmto about 50 mm, to accommodate fetal development and the mature eye oflarger animal models. The reference arm optical path length may beoptimized to correspond with a prescribed range of offsets to a samplearm optical path length as measured to a focal plane of the OCT system.The reference arm path length may generally be selected to be offsetfrom the sample arm path length as measured to a focal plane of the OCTimaging system with a range of 0 mm to 2 mm, and may be less than orgreater than the corresponding sample arm path length.

In still further embodiments of the present invention, at least one lensof the OCT system is provided in the sample arm path and at least onerefracting surface of the subject eye is provided in the sample armpath, the at least one lens and at least one refracting surface of thesubject eye defining an optical system having an optical field curvaturethat matches a physical curvature of a retina of the eye of the subject.The at least one lens may be configured to image a mature eye or animmature eye. A distance from a cornea to a retina of the mature eye maybe about 25 mm and a the distance from the cornea to the retina of thepediatric eye may be from about 14 mm to about 25 mm.

In some embodiments of the present invention, the at least one lens mayhave an associated focus adjustment that enables imaging into bothanterior and posterior portions of the eye of the subject.

In some embodiments of the present invention, the at least one lens mayhave an associated focus adjustment that enables imaging into anteriorregions of the posterior chamber of the eye of the subject.

In further embodiments of the present invention, the system may be awide field imaging system providing a field of view of about 50 degrees.

In still further embodiments of the present invention, the reference armpath length adjustment module may be configured to set a targetreference arm path length based on an age of the subject; a refractivestatus of the eye of the subject; and/or adjust the target reference armpath length based on additional information pertaining to the subject.The additional information pertaining to the subject may includemeasured axial eye length of the subject and/or any relevant testresults.

In some embodiments of the present invention, the OCT system may beportable such that the OCT the system is provided to the subject wherethe subject is located. The portable OCT system may be configured to bemoved to a location of the subject, unplugged and/or receive new sampleswithout being shutdown.

In some embodiments of the present invention, the OCT system may beportable such that the OCT the system is provided to the subject in anyorientation of the subject. The portable OCT system may be aligned tothe subject whether the subject is sitting, standing, lying prone, lyingsupine, at any associated angle.

In further embodiments of the present invention, the portable OCT systemmay include a portable handheld OCT probe; a battery backup deviceassociated with the portable handheld probe; and a moveable rackconfigured to receive the portable handheld probe and/or the batterybackup device.

In still further embodiments of the present invention, the portable OCTsystem may further include a fixation target for the subject configuredto provide a comfort image to the subject during image acquisition. Thefixation target may be configured to provide a continuously variablepatient comfort image. The fixation target may include an image of acharacter, a photograph, or an icon, and the image photograph or iconmay be animated to maintain the subject's attention and relaxation.

In some embodiments of the present invention, the portable OCT systemmay be configured to provide a visible light that reflects off a corneaof the eye of the subject to enable accurate positioning of the portableOCT system.

In further embodiments of the present invention, the portable OCT systemmay include a video and/or digital fundus camera. The video and/ordigital fundus camera may be aligned and calibrated to the OCT system.

In still further embodiments of the present invention, the portable OCTsystem may further include a foot peddle and/or finger triggerconfigured to control focus adjustment, reference arm path lengthadjustment and/or trigger acquisition of an image.

In still further embodiments of the present invention, the portable OCTsystem may further include a foot peddle and/or finger triggerconfigured to control the OCT source power, attenuation of OCT signalpower in the reference arm path, the power of the illumination for thevideo or digital fundus camera.

In some embodiments of the present invention, the portable OCT systemmay be configured to provide two synchronous images to illustrateorthogonal pathology of an eye of the subject to facilitate aiming ofthe portable OCT system during image acquisition.

In further embodiments of the present invention, the portable OCT systemmay be configured to continuously acquire, process and display imagesuntil detection of an image capture trigger signal; and record apredetermined buffered portion of the acquired image upon detection ofthe image capture trigger signal. In certain embodiments, the bufferedimage comprises the most recent from about 2.0 seconds to about 30seconds of the acquired image.

In still further embodiments of the present invention, the continuouslyacquired image may be streamed non-volatile storage for a predeterminedperiod of time.

In some embodiments of the present invention, the system includes aquality-assessing module configured to figure of merit for the qualityof an acquired image; trigger adjustment of the reference arm pathlength and or focusing of at least one lens in the sample arm based onan assessed quality of the displayed image; and trigger the OCT systemto initiate or continue acquisition of the image after adjustments aremade.

In further embodiments of the present invention the OCT system may beconfigured to acquire an image from an aphakic subject that does nothave an ocular lens in the eye being imaged.

In further embodiments of the present invention the OCT system may beconfigured to acquire an image of pathologies that are substantiallyanterior to the posterior pole, or retina of the subject, but stillnominally within the anterior chamber of the eye of the subject. Instill further embodiments of the present invention, the OCT system maybe a pediatric OCT system.

Some embodiments of the present invention provide OCT imaging systemsfor imaging an eye including a source having an associated source armpath and a reference arm having an associated reference arm path coupledto the source path, the reference arm path having an associatedreference arm path length. A sample having an associated sample arm pathcoupled to the source arm and reference arm paths is provided. At leastone lens is provided in the sample arm path, the at least one lenshaving a field curvature that matches a curvature of a retina of the eyeof the subject.

Further embodiments of the present invention provide methods for imagingan eye in an optical coherence tomography (OCT) imaging system includingsetting a target reference arm path length of the OCT system such thatthe reference arm path length is matched to an eye length of a subject;obtaining additional information about the subject relevant to thetarget reference arm path length; recalibrating the reference arm pathlength based on the obtained information; and adjusting the referencearm path length based on the recalibrated reference arm path length.

In still further embodiments of the present invention, an image isacquired using the OCT system having the adjusted reference arm pathlength. The method may further include accessing the image quality ofthe acquired image; determining if the adjusted reference arm pathlength is optimum; further adjusting the reference arm path length if itis determined that the adjusted reference arm path length is notoptimum; and reacquiring the image using the OCT system having thefurther adjusted reference arm path length.

In still further embodiments of the present invention adjusting thereference arm path length is accomplished manually or automaticallybased on feedback from an operator or an image quality metric on anacquired image.

In still further embodiments of the present invention the quality metricis the average or peak brightness of the image.

In some embodiments of the present invention, the steps of accessing,determining, further adjusting and reacquiring may be repeated until animage having a desired quality is obtained.

In further embodiments of the present invention, further adjusting isfollowed by determining if a focus of at least one objective lens of theOCT system is optimum; and adjusting focus position of the at least oneobjective lens of the OCT system if it is determined that the focus ofthe at least one objective lens is not optimum, wherein reacquiring theimage further comprises reacquiring the image using the OCT systemhaving the further adjusted reference arm path length and the adjustedfocus.

In still further embodiments of the present invention adjusting thefocus is accomplished manually or automatically based on feedback froman operator or an image quality metric on an acquired image.

In still further embodiments of the present invention the quality metricis the average or peak brightness of the image.

Still further embodiments of the present invention provide computerprogram products for imaging an eye in OCT imaging systems includingcomputer readable storage medium having computer readable program codeembodied in said medium. The computer readable program code includescomputer readable program code configured to set a target reference armpath length of the OCT system such that the reference arm path length ismatched to an eye length of a subject; computer readable program codeconfigured to obtain additional information about the subject relevantto the target reference arm path length; computer readable program codeconfigured to recalibrate the reference arm path length based on theobtained information; computer readable program code configured toautomatically adjust the reference arm path length based on therecalibrated reference arm path length; and computer readable programcode configured to acquire an image using the OCT system having theadjusted reference arm path length and display the acquired image on anelectronic display associated with the OCT system.

Example embodiments are described above with reference to block diagramsand/or flowchart illustrations of methods, devices, systems and/orcomputer program products. It is understood that a block of the blockdiagrams and/or flowchart illustrations, and combinations of blocks inthe block diagrams and/or flowchart illustrations, can be implemented bycomputer program instructions. These computer program instructions maybe provided to a processor of a general purpose computer, specialpurpose computer, and/or other programmable data processing apparatus toproduce a machine, such that the instructions, which execute via theprocessor of the computer and/or other programmable data processingapparatus, create means (functionality) and/or structure forimplementing the functions/acts specified in the block diagrams and/orflowchart block or blocks.

These computer program instructions may also be stored in acomputer-readable memory that can direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer-readablememory produce an article of manufacture including instructions whichimplement the functions/acts specified in the block diagrams and/orflowchart block or blocks.

The computer program instructions may also be loaded onto a computer orother programmable data processing apparatus to cause a series ofoperational steps to be performed on the computer or other programmableapparatus to produce a computer-implemented process such that theinstructions which execute on the computer or other programmableapparatus provide steps for implementing the functions/acts specified inthe block diagrams and/or flowchart block or blocks.

Accordingly, example embodiments may be implemented in hardware and/orin software (including firmware, resident software, micro-code, etc.).Furthermore, example embodiments may take the form of a computer programproduct on a computer-usable or computer-readable storage medium havingcomputer-usable or computer-readable program code embodied in the mediumfor use by or in connection with an instruction execution system. In thecontext of this document, a computer-usable or computer-readable mediummay be any medium that can contain, store, communicate, propagate, ortransport the program for use by or in connection with the instructionexecution system, apparatus, or device.

The computer-usable or computer-readable medium may be, for example butnot limited to, an electronic, magnetic, optical, electromagnetic,infrared, or semiconductor system, apparatus, device, or propagationmedium. More specific examples (a non-exhaustive list) of thecomputer-readable medium would include the following: an electricalconnection having one or more wires, a portable computer diskette, arandom assess memory (RAM), a read-only memory (ROM), an erasableprogrammable read-only memory (EPROM or Flash memory), an optical fiber,and a portable compact disc read-only memory (CD-ROM). Note that thecomputer-usable or computer-readable medium could even be paper oranother suitable medium upon which the program is printed, as theprogram can be electronically captured, via, for instance, opticalscanning of the paper or other medium, then compiled, interpreted, orotherwise processed in a suitable manner, if necessary, and then storedin a computer memory.

Computer program code for carrying out operations of data processingsystems discussed herein may be written in a high-level programminglanguage, such as Java, AJAX (Asynchronous JavaScript), C, and/or C++,for development convenience. In addition, computer program code forcarrying out operations of example embodiments may also be written inother programming languages, such as, but not limited to, interpretedlanguages. Some modules or routines may be written in assembly languageor even micro-code to enhance performance and/or memory usage. However,embodiments are not limited to a particular programming language. Itwill be further appreciated that the functionality of any or all of theprogram modules may also be implemented using discrete hardwarecomponents, one or more application specific integrated circuits(ASICs), or a programmed digital signal processor or microcontroller.

It should also be noted that in some alternate implementations, thefunctions/acts noted in the blocks may occur out of the order noted inthe flowcharts. For example, two blocks shown in succession may in factbe executed substantially concurrently or the blocks may sometimes beexecuted in the reverse order, depending upon the functionality/actsinvolved. Moreover, the functionality of a given block of the flowchartsand/or block diagrams may be separated into multiple blocks and/or thefunctionality of two or more blocks of the flowcharts and/or blockdiagrams may be at least partially integrated.

In the drawings and specification, there have been disclosed exemplaryembodiments of the invention. However, many variations and modificationscan be made to these embodiments without substantially departing fromthe principles of the present invention. Accordingly, although specificterms are used, they are used in a generic and descriptive sense onlyand not for purposes of limitation, the scope of the invention beingdefined by the following claims.

That which is claimed is:
 1. An optical coherence tomography (OCT)imaging system for imaging an eye, the system comprising: a sourcehaving an associated source arm path; a reference arm having anassociated reference arm path coupled to the source path, the referencearm path having an associated reference arm path length; a sample havingan associated sample arm path coupled to the source arm and referencearm paths; and a reference arm path length adjustment module coupled tothe reference arm, the reference arm path length adjustment moduleconfigured to automatically adjust the reference arm path length suchthat the reference arm path length is based on an eye length of thesubject.